This is really heating up. Stay tuned for further developments as Congress is emboldened by the SEC civil fraud charges:

Washington is suddenly looking very unkind to the firm that used to be known as "Government Sachs." Now the Senate's Permanent Subcommittee on Investigations, led by Carl Levin, Democrat of Michigan, is planning to focus hearings scheduled for next week at least in part on Goldman Sachs's role in the financial disaster.

Levin's staff has uncovered new documents "that link certain actions to specific people" at Goldman, according to a senior legislative official who spoke on condition of anonymity. The official would not divulge the nature of the allegation but said that Levin believes it amounts to "another big shoe to drop on Goldman."

Spokespeople for Levin said they were not prepared to discuss the nature of the probe, but his committee has been conducting several weeks of hearings and one is planned for April 27 on "the role of the investment banks." "We expect to have some information tomorrow," spokesman Bryan Thomas said Monday.

To a layperson, the case against Goldman may seem clear cut. After all, investors did not know some information about the product that they might have considered vital, and they lost $1 billion in the end. But the rules that govern these kinds of transactions are not so plain.

Several experts on securities law said fraud cases like this one, which focuses on context rather than content, are generally more difficult to win, because it can be hard to persuade a jury that the missing information might have led buyers to walk away.

They added, however, that the strength of the S.E.C.’s case is impossible to gauge until the agency discloses more of the evidence it has assembled. So far it has provided only a sketch.